The present invention relates to a fluid pressure equipment with a position indicating mechanism, which is provided with a piston which operates according to fluid pressure to drive a load and a position indicating mechanism which indicates an operation position of the piston.
As a fluid pressure equipment provided with a piston which operates according to action of fluid pressure, there are generally known an ordinary fluid pressure cylinder which drives an external load by a rod extending from the piston, a switching valve which is constituted so as to drive a valve member of a spool type or a poppet type, which switches flow paths for fluid, by the piston operating according to fluid pressure, and the like.
In such a fluid pressure equipment, a magnetic sensor is usually used as means for detecting an operation position of the piston and magnetic from a magnet attached to the piston is detected by the magnetic sensor so that it is detected that the piston has reached a stroke end.
However, in a conventional position detecting system using such a magnetic sensor, it is common to electrically process a detection signal outputted from the magnetic sensor by a signal processing circuit and utilize the processed signal to indicate the operation position of the piston on such display means as a light emitting diode or the like. Therefore, the system requires the complicated signal processing circuit, the display means and the like, and it can not be caused to easily indicate the operation position of the piston on the fluid pressure equipment which accommodates the piston therein.
A technical object of the present invention is to provide a simple position indicating mechanism to a fluid pressure equipment housing a piston therein in an additional manner, thereby allow the operation position of the piston to be viewed on the fluid pressure equipment indirectly.
According to the present invention for solving the above-described problem, there is provided a fluid pressure equipment with a position indicating mechanism, comprising a piston which slides in the interior of a casing according to action of fluid pressure to drive a load and an indicator which displaces due to a magnetic attracting force following the piston, wherein the indicator is provided on the casing so as to be visible from the outside.
According to such a fluid pressure equipment of the present invention, the indicator is provided on the casing so as to be visible from the outside and the indicator is caused to displace due to action of magnetic attracting force following the piston, so that the operation position of the piston can be viewed indirectly through the indicator without using such a complicated apparatus as a magnetic sensor or a signal processing circuit. In addition, since not only the position of the piston positioned at a stroke end but also the position thereof positioned in the course of the stroke can be indicated, when the piston has stopped in the course of the stroke due to a malfunction, the malfunction can be found through the indicator.
According to a preferred specific constitution aspect of the present invention, a magnet and a magnetic body mutually attracting each other are provided on at least one portion of the indicator and the piston, a guide groove extending in a direction of a moving direction of the piston is formed on an outer face of the casing, and the indicator is received in the guide groove so as to be movable in a state that a portion thereof has been exposed to the outside.
In this case, it is preferable that the guide groove is formed such that the width of the interior of the groove has a sectional shape wider than the width of an opening portion of the groove, the indicator is formed in a short column shape having a diameter larger than the width of the opening portion of the groove, and the indicator is received in the interior of the groove so as to be visible through the opening portion of the groove.
A marking indicating the operation position of the piston can be attached to the casing along the guide groove.
According to one constitution aspect of the present invention, such a constitution is constituted that the casing is provided with a plurality of ports, flow paths which connect these ports, and a valve member which switches communication states of the flow paths, and the piston drives the valve member as a load.
According to anther constitution aspect of the present invention, such a constitution is employed that the piston has a rod extending outside the casing, and an external load is driven by the rod.
According to still another constitution aspect of the present invention, there is provided a fluid pressure equipment with a position indicating mechanism, comprising: a valve mechanism portion having a plurality of main ports, flow paths which connect the main ports and a valve member which switches communication states of the flow paths; a cylinder portion having a piston slidable in a cylinder hole, pressure chambers formed on both sides of the piston, a plurality of operation ports communicating with the pressure chambers, and a rod coupling the piston and the valve member; and a position indicating mechanism which indicates the operation position of the piston, wherein the position indicating mechanism has the indicator.
The guide groove can also serve as an attaching groove for attaching a magnetic sensor.